The human skeleton consists of more than 200 bones. All of them perform a certain function, on the whole creating a support for external and internal organs. Depending on the load and role in the body, there are several types of them.
Bone structure
In dry form, 1/3 of human bone consists of organic matter - ostein protein. It provides its flexibility and resilience. 2/3 are inorganic calcium salts, due to which their strength is achieved.
The outer shell is the so-called compact substance. These are dense scales of bony tissue. Their densest layer can be observed in the center of the tubular bones. To their edges the compact substance becomes thinner.
Depending on the type of bones, their inner part can consist of either spongy substance, white bone marrow, or can be filled with air. The spongy bones, in addition, also have red bone marrow.
At the ends, nerves and blood vessels enter the bone, which bind it to the whole body and provide nutrition, growth and recovery.
Varieties of bones of the human body
By structure, the bones are divided into spongy, tubular and pneumatic. Tubular called still long. They are present in the skeleton of the limbs and are responsible for their movement. These bones are composed of a compact substance and a cavity filled with yellow bone marrow. At the ends they have a little spongy substance filled with red bone marrow.
The spongy bones of a person are completely composed of spongy substance with red bone marrow inside, they are covered with a compact substance. They form cavities (chest, cranial) and serve as a support in places with the greatest load (spine, phalanx of the fingers).
Pneumatic bones have a special structure: inside the compact substance there is a cavity, which is covered by the epithelium and filled with air. An example is the skeleton of the upper jaw.
Spongy bones: detailed diagram
As already noted, basically the structure of the trabecular bone is practically no different from others. This is a cavity formed by a compact substance and filled with a sponge. By origin, they are different. The bones of the ribs, for example, are formed from cartilage, and the lids of the skull from the connective.
A spongy substance consists of many thin bony septa directed in accordance with the movement of substances in the bone. This structure allows you to achieve greater strength from the bones. They are less likely to break and crack.
At the edges of the bones there is cartilaginous tissue through which nutrients enter and the nerve endings penetrate.
The spongy cavity is filled with red bone marrow, which is responsible for the formation of red blood cells. This pattern of the cancellous bone allows it to perform several very important functions at once.
Varieties
In the structure of the human skeleton, spongy bones have a quantitative advantage. Therefore, scientists distinguish several of their varieties.
Distinguish between flat and voluminous bones. Flat form the lid of the cranium and pelvic cavity. This includes the shoulder blades. Voluminous are represented by ribs and phalanges of the fingers. The vertebrae are of the mixed type, since their body consists of a voluminous tubular bone, and the appendix is flat.
In size, it is customary to distinguish long and short spongy bones. The ribs are considered one of the longest. The short ones include the bones of the phalanges of the fingers and toes.
A unique bone can be called a scapula. It is attached to the body only with the help of connective tissues, while most bones are connected by joints.
Functions of the spongy bones
The first and main function that the spongy bones perform is the supporting one. They create the basic framework of the human skeleton. The vertebrae form the spine, supporting the entire body in an upright position. The bones of the foot hold the entire body weight.
The second function is protective. The spongy bones of a person create and surround cavities, protecting their contents from external damage. This is the cover of the skull, ribs and pelvic bones.
The motor function is carried out by the bones of the phalanges of the toes and hands.
With metabolic disorders, bones can become very fragile or extremely durable. In both cases, it is dangerous for normal human life.
The internal filling of the bones - bone marrow - plays a major role in the formation of blood.
The value of red bone marrow
In the human body, the pattern of the cancellous bone implies the obligatory presence of red bone marrow in it . This substance is so important for life that it is present even in the tubular bones, but in a smaller amount.
In childhood, the spongy and tubular bones are equally filled with this substance, but with age, the tubular cavities are gradually filled with yellow bony marrow.
The main task of the red bone marrow is the synthesis of red blood cells. As you know, these cells do not have a nucleus and cannot divide themselves. In the spongy substance, they ripen and enter the bloodstream during metabolism in the bones.
Impaired functioning of the red bone marrow entails diseases such as anemia and varieties of blood cancer. Often, drug treatment is not effective and you have to resort to red brain transplantation.
This substance is very sensitive to radiation. Therefore, many victims of it have precisely various forms of blood cancer. The same property is used in transplantology when it is necessary to kill infected bone marrow cells.
Possible damage
By nature, the structure of the cancellous bone allows it to be quite resistant to mechanical damage. But often there are times when the integrity of the bone is broken.
Compression fractures are characterized by compression of the bone due to the strong impact on it. The vertebrae are very susceptible to this type of damage. You can get injured during an unsuccessful landing on your feet or falling. The danger of a fracture is that the vertebra ceases to protect the spinal cord, which can lead to damage.
Since most of the long, spongy bones are curved, they can crack during a hard hit on hard objects. Such damage is relatively safe. With timely medical care, the cracks heal quite quickly.
Spongy bones may break. In some cases, injuries of this kind are practically not dangerous. If there was no bias, they are restored quite quickly. The danger is those bones that, during a fracture, can move and pierce vital organs. In this case, a relatively harmless fracture causes disability and death.
Bones and age-related changes
Like all other human organs, spongy bones are subject to age-related changes. At birth, some of the future bones have either not yet strengthened, or have not formed from cartilage and connective tissue.
Over the years, bones tend to “dry out”. This means that in their composition the amount of organic substances becomes less, while minerals replace them. Bones become fragile and recover longer after damage.
The number of bone marrow is also gradually decreasing. Therefore, older people are prone to anemia.